Removal of low-concentration sulfide in clean rooms is important in the semiconductor industry. In dry conditions, silver–manganese exchanged Y zeolite (Ag–Mn/Na-Y) has high removal efficiency and high saturation adsorption capacity towards dimethylsulfide (DMS). However, the removal efficiency of DMS on Ag–Mn/Na-Y decreases with increasing water concentration in inlet gas at room temperature and normal pressure. In high humidity conditions, the removal efficiency and saturation adsorption capacity of DMS is high for silver–manganese exchanged ZSM zeolite (Ag–Mn/ZSM-5). In this paper, the influence of water concentration on the removal efficiency of DMS on Ag–Mn/zeolites was examined. The variations of functional group detected in FT-IR spectroscopy and temperature programmed desorption (TPD) confirm that water molecules influence the ability of DMS adsorption by Ag–Mn/zeolites.